四種LED交通標誌設計;Evaluations on Four Different Designs of LED Traffic Signs

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/75225

Title:	四種LED交通標誌設計;Evaluations on Four Different Designs of LED Traffic Signs
Authors:	黃鼎元;Huang, Ting-Yuan
Contributors:	光電科學與工程學系
Keywords:	LED交通標誌;眩光;顯示舒適度;標誌判別度;喜好度;LED traffic signs;Glare;Visual comfort;Legibility;Preferences
Date:	2017-08-28
Issue Date:	2017-10-27 17:20:46 (UTC+8)
Publisher:	國立中央大學
Abstract:	現今LED已普及化，LED交通標誌與號誌出現在道路上越來越多，但設計的方式並無統一規範。根據現有製作工藝技術，本研究評估四種可行的LED標誌設計方案，包括LED外部照明、LED局部側背光、LED側背光與LED燈箱直下背光，探討何種設計擁有最佳視覺感受。　　本研究的LED交通標誌人因實驗以四種標誌為實驗因子，牌面大小為實體標誌的六分之一，觀測距離為25公尺。實驗設計的輝度範圍符合經濟部能源局之LED交通標誌輝度規範，內部照明式標誌設置為200-350 nit，照度符合交通工程規範之標誌照明規範，外部照明式標誌設置為400 lux，並以顯示舒適度、標誌判別度、喜好度與排名順序，得到受試者的主觀評量分數。　　實驗分析方式將受試者的主觀評量匯入統計軟體，結果顯示，四種標誌的因子達顯著水準，事後檢定結果顯示內部照明式是被受試者認為較清楚與舒適，且較為喜愛，外部照明式相對視覺感受較差，排名最後。接著對內部照明式進行後續分析，發現環境背景照度是影響視覺品質的一項因素，其中局部側背光式最容易受到環境背景照度影響，因標誌綠色底色無點亮，僅靠環境光源投射在反光片上以提供亮度，而側背光式和燈箱直下式皆為點亮整個牌面，受到環境背景照度的影響較少，兩者比較的結果顯示，燈箱直下式的視覺感受優於側背光式。以本研究所探討的四種LED交通標誌設計，建議未來設置LED交通標誌以燈箱式為優先。 ;LEDs have been widely used in lighting applications, including traffic signs and traffic signals. Yet the design of LED traffic signs has no universal specifications. This study evaluates four custom-made LED highway traffic signs with different designs, including external LED lighting, LED backlight, regional LED backlight and LED lightbox. Participant observation studies were performed to investigate which design would have the best visual quality. The ergonomic experiments use the four LED traffic signs as the experimental factor. The signage dimension is one-sixth of the real traffic signs, and the observation distance is 25 m. The luminance range of internal lighting signs is set at 200-350 nit, which complies with the “Technical Regulations of LED Road Traffic Signs” published by the Bureau of Energy, Ministry of Economic Affairs. The illuminance on the non-self-luminous sign with external LED lighting is set to 400 lux, within the range regulated by the “Road Traffic Construction Regulations” enacted by the Ministry of Transportation and Communications. We collected subjective scores from the participants, including the legibility, visual comfort, preferences and ranking. The subjective scores were analyzed by the statistical software. The results showed that self-luminous traffic signs provide superior legibility, visual comfort, preferences and ranking than the non-self-luminous one. We also found the ambient illumination a key factor affecting the visual quality. Among the traffic signs self-luminous with LEDs, regional LED backlight is most susceptible to the ambient illumination because the green background is not lit. The green background relies on the ambient illumination to project on the retroreflective sheet to provide brightness. A small variation in the ambient illumination would result in tremendous change to the visual performance of regional LED backlight. Both LED lightbox and LED backlight light up the whole signage area and provide similar visual sensations to the participants, with the subjective scores of LED lightbox significantly better than that of LED backlight. Based on the four LED traffic signs designed and evaluated in this study, we suggest to use LED lightbox for future installations of LED traffic signs.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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